Digital BW, The Print

Walt,

I don't think the utility of the program is reduced.  Rather, the  
measurement data are faulty, for whatever reason, and should not be  
used in an attempt to generate an icc profile.  I think you should  
instead try to correct the printing problem (e.g. adjust ink limits,  
ink overlap, partitioning, etc.) that is producing the aberrant  
measurements.

Carl

On Oct 18, 2005, at 11:43 AM, wwodets wrote:

> Carl and Steve:
>
> This is exactly the problem I mentioned in an earlier post about
> profiling the Arches Smooth paper.  The Lab values were linear up to
> a 90% gray.  After that (for the 92, 94, 96, 98 and 100% gray) LAB
> values read: 19.39, 19.06, 18.70, 18.95, 19.39.  Rather than
> correcting this nonlinearity, Create ICC produced an unusable profile
> with a full scale, retangular spike between LAB 0 and LAB 8 (e.g. LAB
> 5 was "corrected" to LAB 98).  So this supports Carl's description of
> function (and, I think, reduces the utility of the program).
>
> The abnormailty in this case was produced, I think, by the way the
> ink sits on the Arches coating: way too wet.
>
> Walt
>
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Carl Schofield
> <scho@m...> wrote:
>
>>
>> Steve,
>>
>> Yes, I tried it and it works well.  It assumes you have values from
>>
> 0
>
>> to 100 and just scales accordingly (after sorting).  There is a
>> potential for error if your D values (or inversely L values) to
>>
> not
>
>> increase with increasing gray values, but that would be abnormal.
>>
>> Carl
>>
>> On Oct 18, 2005, at 9:34 AM, Steve Kale wrote:
>>
>>
>>> Actually Carl are you sure about this?  It should also need the
>>> Gray value
>>> else it does not know for what input the output was generated.
>>>
>>>
>>>
>>>
>>>> From: Carl Schofield <scho@m...>
>>>> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
>>>> Date: Tue, 18 Oct 2005 08:45:08 -0400
>>>> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
>>>> Subject: Re: [Digital BW] ICC v. Transfer Function in Epson
>>>>
> driver
>
>>>>
>>>> Paul,
>>>>
>>>> You don't need all of the data columns.  Just a single column of
>>>> either visual density (labeled either D or V) or Lab L (L label)
>>>> data.  The icc-create droplet will simply assume zero values for
>>>>
> Lab
>
>>>> a and Lab b if no actual data are present.  The density or L
>>>>
> values
>
>>>> can also be in any order and will be automatically sorted (high
>>>>
> to
>
>>>> low for L and low to high for D).  This with the 2.3.1 version
>>>>
> on a
>
>>>> Mac but I assume it is the same for the PC version.
>>>>
>>>> Carl
>>>>
>>>>
>>>